FunctionsCourse skill

Constructing a quadratic from zeros and a point

Use the zeros for the factors and a known point for the scale factor.

  • Zeros and give .
  • Substitute the known point to find .
  • Keep the factorised form when it displays the zeros clearly.

Example 1

Find the scale factor

Find the quadratic function with the stated zeros and point. Zeros 1 and 4; passes through .

Example 2

Find the quadratic function with the stated zeros and point. Zeros and ; passes through .

Your turn

5 practice questions
Question 1

The zeros are 2 and 5. The graph passes through . Find a factorised equation.

Check answer
Question 2

The zeros are -1 and 3. The graph passes through . Find a factorised equation.

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Question 3

The zeros are -2 and 4. The graph passes through . Find a factorised equation.

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Question 4

The zeros are 1 and 6. The graph passes through . Find a factorised equation.

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Question 5

The zeros are -3 and -1. The graph passes through . Find a factorised equation.

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